You want to create a macro. Hit "ctrl+q" to begin recording the macro. Then hit the key combination you want to record. In your case, "end" -> "enter". Then press "ctrl"q" again. Now go to "Tools -> Save Macro". Save this in your user directory (it should default there I believe). Finally create a user keybinding with the following entry.

The above is kind of a general flow for defining/using a custom macro (series of commands). For your specific use case, I think the built in "Add Line" macro should do what you want. Just try adding the following as a user keybinding.